Direct Comparison of Subvalent, Polycationic Group 13 Cluster Compounds: Lessons learned on Isoelectronic DMPE Substituted Gallium and Indium Tetracation Salts

Abstract

The tetracationic, univalent cluster compounds [{M(dmpe)}4]4+ (M=Ga, In; dmpe=bis(dimethylphosphino)ethane) were synthesized as their pf salts ([pf]−=[Al(ORF)4]−; RF=C(CF3)3). The four‐membered ring in [{M(dmpe)}4]4+ is slightly puckered for M=Ga and almost square planar for M=In. Yet, although structurally similar, only the gallium cluster is prevalent in solution, while the indium cluster forms temperature dependent equilibria that include even the monomeric cation [In(dmpe)]+. This system is the first report of one and the same ligand inducing formation of isoelectronic and isostructural gallium/indium cluster cations. The system allows to study systematically analogies and differences with thermodynamic considerations and bonding analyses, but also to outline perspectives for bond activation using cationic, subvalent group 13 clusters.

Structures, Bonding Analyses and Reactivity of a Dicationic Digallene and Diindene Mimicking trans‐bent Ditetrylenes

“…Upon changing to M=Ga, conversion of P 4 into the cyclic triphosphenium cation [C 2 H 4 (PCy 2 ) 2 P] + was observed via 31 P NMR spectroscopy (ESI, section 5.5). Despite of the formation of another unidentified major product, this compares well with the formation of an analogous phosphenium cation that was previously observed when mixing [In(dmpe)] + with P 4 [36] . This suggests that the formation of phosphenium cations may be a general reaction pathway of P 4 and cationic, subvalent, group 13 complexes with bis phosphine ligands.…”

From mixed group 13 cations [M(AlCp*)3]+ (M = Ga/In/Tl) to an Al4+ cluster

“… 35 and [Ga 4 (dmpe) 4 ] 4+ (2.485 Å (avg.)). 36 Notably, in the latter complexes the gallium cations are only coordinated by two strongly electron donating ligands that induce cluster formation via delocalization of the cationic charge onto the ligand. In contrast to 1, the [In(AlCp*) 3 ] + cations in 2 form coordination oligomers with the indium atom loosely coordinating to the Cp*-ligand of a neighbouring cation.…”

Strukturen, Bindungsanalyse und Reaktivität eines dikationischen Digallens und eines Diindens, die trans‐gefaltete Ditetrylene nachahmen

“…Trotz der Bildung eines weiteren, nicht identifizierten Hauptprodukts ist dies vergleichbar mit der Bildung eines analogen Phospheniumkations, das zuvor beim Mischen von [In(dmpe)] + mit P 4 beobachtet wurde. [36] Dies deutet darauf hin, dass die Bildung von Phospheniumkationen ein allgemeiner Reaktionsweg von P 4 und kationischen, subvalenten Komplexen der Gruppe 13 mit Bisphosphinliganden sein könnte. Im Gegensatz dazu reagiert [{Ga(dcpe)} 2 ] 2 + bei rt leicht mit 1-Hexen, Cyclooctin, Diphenyldisulfid und Diphenylphosphan.…”